Kaplan SAT Literature VS Barron's VS real thing

I picked up, among other things, the Barron's (forget which edition) and 10th edition Kaplan SAT Literature books earlier today. I took the first practice test (the "diagnostic test") in the Kaplan and only got a 500!!!

I feel retarded. :(

Is Kaplan's harder than the real thing? Is Barron's better?